main: split off reading and usage function to its own unit

include/arl/cli.h

@@ -0,0 +1,31 @@
+/* cli.h: CLI helpers
+ * Created: 2026-01-29
+ * Author: Aryadev Chavali
+ * License: See end of file
+ * Commentary:
+ */
+
+#ifndef CLI_H
+#define CLI_H
+
+#include <stdio.h>
+
+#include <arl/lib/sv.h>
+
+int read_file(const char *filename, sv_t *ret);
+int read_pipe(FILE *pipe, sv_t *ret);
+void usage(FILE *fp);
+
+#endif
+
+/* Copyright (C) 2026 Aryadev Chavali
+
+ * This program is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE.  See the MIT License for details.
+
+ * You may distribute and modify this code under the terms of the MIT License,
+ * which you should have received a copy of along with this program.  If not,
+ * please go to <https://opensource.org/license/MIT>.
+
+ */